Reinforcing member for heterogeneous beams



6 Sheets-Sheet 1 ZONE 0F FULL COMPRESSION CEN ER DIRECT STEEL W rm July25, 1939. J. McLAFFERTY I REINFORCING MEMBER FOR HETEROGENEOUS BEAMSFiled NOV. 19, 1936 Locus or CENTERS OF PRESSURE Yd L M N TE R0 1" A m 5M FF I 0R F P 0 EE M an 0 W C u C R E T N E c M L w M M UI m un .w FM nO G P. mm 4 0C 2 LOCUS OF CENTERS F PRESSURE LONGITUDINAL BEAM CENTERLINE July 25, 1939. J. E. McLAFFERTY 2,167,029

REINFORGING MEMBER FOR HETEROGENEOUS BEAMS Filed Nov. 19, 1936 eSheets-Sheet 2 acyza jzfinfvr: Jazzy/$456 7 y 25, 1939- J. E. McLAFFERTY2,167,029

REINFORCING MEMBER FOR HETEROGENEOUS BEAMS Filed Nov. 19, 1936 6Sheets-Sheet 3 J. E. M LAFFERTY REINFORGING MEMBER FOR HETEROGENEOUSBEAMS July 25, 1939.

6 Sheets-Sheet 4 QzyJJ Filed Nov. 19, 1956 a yJ/J fi/e fifor. Z? we? 17M' jafferg Z AQM'A, Mvm J I 6.

y 25, 1939- J. E. MOLAFFERTY 2,157,029

REINFORGING MEMBER FOR HETEROGENEOUS BEAMS Filed Nov. 19, 1936 6Sheets-Sheet 5 x 7 t A55 A542 D921 a i Mi f] m m Jul 25, 1939.

J. E. M LAFFERTY REINFORGING MEMBER FOR HETEROGENEOUS BEAMS 6Sheets-Sheet 6 Filed NOV. 19, 1936 mq ff Patented July 25, 1939 eArENTOFFICE REINFORCIN G MEMBER; FOR HETEROGENE- OUS BEAMS Joel E.McLaiferty, Omaha, Nebr. Application November 19, 1936, Serial No.111,608

37 Claims.

My invention relates to a structural member intended as a reinforcingunit for concrete, masonry, or other heterogeneous structural mem bers,including fabricated joists, in which the components are disposed tomore effectively resist the applied stresses, one phase of the inventionbeing concerned more particularly with reinforced concrete constructionswhich are adapted to carry loads considerably in excess of thatpermitted by present practice, and which is further characterized by arelatively large saving in weight of the reinforcing unit.

The art of reinforcing members for heterogeneous beams comprisesgenerally two systems which may be termed the compact and the loose barsystems. These systems are broadly deficient in respect of fulfillingeither one or both of the following fundamental requirements for maximumstrength, namely, that the bars should be fastened together in such amanner that the tensile stresses will not be transferred from onereinforcing element to another through the concrete, and that thetensile element should be properly disposed in the body of the beam toobtain the most effective results.

In the compact bar'system, which is now practically obsolete, thetensile elements are clamped or mechanically fastened together to form acompact section at the point of maximum moment, with the ends into thebody of the beam to accommodate diagonal tension stresses. It is wellknown that this system, spite of its theoretical economy, has not beenaccepted by the engineering profession because of its low loadresistance.

The loose bar system, which is in general use at the present time,comprises a combination of straight bars, bent bars, and stirrups. Thissystem not only requires considerable labor to insure its correcttheoretical positionduring the pouring of the concrete, but the straightbars and bent bars, which are provided for direct tension requirement,must be separated in the bottom of the beam in order to provide surfaceareas for bonding with the concrete. Accordingly, not only is the sizeof the beam increased, but the strength of the beam is impaired bysubjecting the concrete to tension in transferring the stress from onebar to another.

Another serious objection to these systems is that no restraint isplaced on the flow of concrete in the region of an intermediate supportin a continuous beam. The compact system does not offer any restraint,while the loose bar system, with the lapping of straight bars, bentbars, and

of the elements diverging stirrups, forms substantially a fence Withoutfastened corners.

In order to obtain maximum test results, the reinforcing must bedisposed in the direction of the stresses and its component elementsmust also be restrained against slipping so that they will be able toadequately carry the stresses.

Some of the compact systems have approximated the correct direction ofthe stresses, but have failed to properly fasten the elements togetherto prevent relative slippage.

The bars in the loose bar system cannot possibly follow the properdirection of the diagonal tension stresses, nor are there any devices toprevent slippage. Properly curved and properly fastened reinforcingelements may be compared to the root system of a tree or to a sack ofgrain. They can be made to crowd the concrete in tne bottom of a beaminto compression if methods outlined in my invention are followed.

It is therefore one of the objects of my invention to devise a moreeflicient structural member having a laminated construction, the memberbeing composed of a plurality of bars which are positively secured toeach other intermediate their ends, as by welding, to prevent relativeslippage and to form a substantially single bar, the ends of the barsbeing curved to resist any slipping action thereof under load.

A further object is to provide a member of the character indicated inwhich the bars may be bent as they are no longer required in directtension and as they may be required for shear or diagonal tension,certain of the bars,. particularly those closer to the center of thebeam being curved to more effectively resist the diagonal ten sionstresses, and the ends of the bent bars, where design conditionsrequire, being provided with hooks to resist and prevent flow of theconcrete in that region.

A further object is to devise a structuralmemher in which the componentelements are arranged to definitely prevent the transfer of stress fromone bar to the next through shear or tension in the concrete, therebyeliminating secondary stresses.

A further object is to devise a reinforcing member for concrete beams inwhich the composing bars are arranged to definitely place a considerableportion of the concrete portion of the beam in compression, so that moreof the compressive strength of the concrete can be depended upon than isnow current in standard practice.

A further object is to devise a reinforcing member having a laminatedconstruction for concrete beams wherein the several members may bedefinitely fixed against displacement at the point of manufacture, sothat when delivered at the point Where required, absolute assurance ishad, not only that the component elements occupy their correctpositions, as determined by the designer,

but that these positions will not be disturbed by.

7 is utilized to increase the compressive strength of the concrete. 7

The present application is'a continuation in part of my copendingapplication for a reinforcing member for heterogeneous beams, Serial No.674,844,1iled June 8, 1933.

The design of my improved structural member is based upon a noveltheoretical consideration of the stresses operating in a beam whichdiffers in certain respects from the principles now applied in the 'art.A brief discussion of this theory will be given hereinafter, togetherwith a number of formulas which may be employed in the manner indicatedto determine the amount and direction of the stresses operating indifferent portions of the beam, from which the disposition and shapingof the component elements of the strucmore effectively resist thestresses than is now' tural member may be determined. Attention will nowbe given to a general discussion of the advantages flowing from the useof myimproved structure and the manner in which it operates, in

conjunction with the concrete, for example, to

sustain the applied load.

As stated hereinbefore, myimproved structure has its component elementsdisposed so as to current in standard practice, and actual tests haveshown that concrete beams reinforced with this unit'have carried, andmay be expected by rational theory to carry, loads substantially doublethat contemplated by present systems of reinforcing which have beendesigned according to accepted formulas. Moreover, this additionalstrength issecured notwithstanding a saving of from 15 to leper cent inthe weight of the reinforcing metal. Because of its. greater effectiveness in resisting stresses and itscompact nature, it is possible to makeconcrete beams of a smaller size than withpresent systems. Besides, whenused under conditions requiring fireproof construction and the use of aconcrete slab,'this unit will produce a concrete beam capable ofcarrying as great or greater safe loads than present stand ard, stocksized', structural beams with th'e'same outside dimensions over the same'fireproofing requirements. 7 One of the outstanding advantages of theunit is its capacity for rnaking an adequate bond with in the concrete.In the region of maximum moment in the beam, the unit may beconcentrated into a small size, while toward'the end of the perimeter ofthe unit may be increased greatly over the perimeter at the point ofmaximum moment by bending the bars as they are no longer required inhorizontal'tension and as they may be required for shear or diagonaltension. In the controlling maximum moment section, it is unnecessary towaste any space in allowing for the passage of concrete around theindividual bars, since, at this point in the beam, the individual barsof the unit are arranged in a laminated construction with the barssecurely fixed to each other.

One of the most important requirements in a concrete reinforcement isthat the strengthening members which are intended to resist the shear ordiagonal tension stresses should be sufliciently long to have anadequate anchorage in the compression side of the beam and so disposedthat they will transmit these stresses to the main tensionreinforcement. In my improved construction, for simple beams, the unithas the ends of the elements bent to the proper shape to conform to thedirectionof the diagonal tension stresses, while over the support, aspecial unit is provided which gives anchorage in the bottom side whenthe bending moment is reversed over the support, thus obtaininganchorage in the compression side in all cases. By employing the ends ofthe direct tension elements to resist diagonal tension, it is. obviousthat material is not wasted in developing the ends of'two separatemembers by anchorage in the concrete.

My product is particularly desirable from the standpoint of the designerdue to its greater load resistance and the fact that the correctposition ing of the reinforcing element is maintained under conditionsof rough handling. Fewer pieces makes for a more compact reinforcingwith re sulting saving in weight of metal and volume of concrete,andwith consequent reduction in beam, column and footing sizes.

The laminatedconstruction of my unit enables the component elements tobe securely fastened .to each other, as by welding, in order to preventany possible relative slippage when the beam is subjected to stress,thus providing a unitary con struction in that portion of the unitwhich'is welded. For those bars which are bent upwardly,

beams is the determination of the direction of the diagonal tensionelements. Present practice does not provide for this factor which iseven more important than the strength of these elements.

According to present design, the diagonal tension elements arearrangedin parallel relation notr or downwardly, as, the case may be,the drop-off withstanding the fact that the actual direction a of thestresses varies according to the conditions prevailing at the pointunder consideration. It will be shown that the nature of the shape ofthe diagonal tension elements should vary according to the conditionsprevailing both along the direct tension side of the beam and also alongthe direct compression side.

My improved reinforcing device so disposes the diagonal tension elementsnear the region of -maximum moment that they will transmit compressivestress into the body of the beans By curving the prongs, or diagonaltension elements,

prongs will crowd the concrete in the bottom of the beam intocompression, instead of permitting the concrete to stretch with themaintension steel, and will also crowd the concrete in the 75 7 o asdetermined by formulas given hereinafter, the

compressive side of the beam into greater compressive resistance.

Accordingly, if we consider a beam which is provided with a reinforcingunit having a number of properly curved bars, then, as the loadincreases on the beam, more and more portions of the curved diagonaltension elements near the point of maximum moment come into action. Whenthe amount of steel in the beam is sufficient, these curved elements orprongs bind around the enclosed concrete and restrain it from bulging orflowing out at the bottom in a manner somewhat analogous to the actionof a sack containing grain. This action, not only results in bringingthe compression zone of the beam down to the steel reinforcement, butproper design can insure of the concrete from the top of the beam to thecenter of the steel reinforcing being placed in uniform compression.Moreover, this curving of the several prongs prevents the concrete inthe bottom of the beam from flowing or stretching with the bottom steeland therefore results in from 40120 100 per cent greater strength thanis now possible with standard systems which are not provided withcompressive reinforcement.

With my unit, it is not only possible to increase the bending resistanceof a beam, but also to very considerably increase the shearing ordiagonal tension resistance. If the tension elements in the ends of aconcrete beam are placed in the amounts and directions in which thetensile stresses occur, the concrete will be in simple diagonalcompression at the ends of the beam and should carry as high a unitstress in that region as it carries in the center of the beam at thepoint of maximum moment. For example, ifa beam were stressed up to 1000pounds per square inch in diagonal compression, it would have an averageshearing stress of 667 pounds per square inch. According to currentspecifications, however, which are based on experimental data, anallowable unit of shearing stress is 150 pounds per square inchordinarily and, under special circumstances, as high as 300 pounds persquare inch is permitted, in comparison with an allowable compressivestress of 1000 pounds per square inchat the center. If we consider thedistance from the center of the steel to the center of the compressiveforces as three-fourths the depth of the beam, the average intensity ofshearing stress would be 225 pounds per square inch compared with 667pounds per square inch. This condition indicates that it is possible toincrease the shearing resistance from two and onehalf to three times theextreme anticipations of present specifications. Actual tests made withbeams having the reinforcing constructed according to my formulas haveproduced results that averaged more than one and three-fourths times thepresent data.

My improved type of reinforcement also finds special application in aconcrete T-beam, where it is possible to use a plane curved, or athreedimensional curved reinforcement to secure against the shearingstresses between the web and the T. This construction is definitelynovel in T-reinforcements. It has not been recognized that the directionof the resultant tensile stress is a combination of the tendency of theT to shear off horizontally and the tendency of the web to deflectvertically. My improved unit materially strengthens this type of beambecause the reinforcing can be correctly placed in accordance with theactual direction of the resultant forces.

In connection with beams which rests on an intervening support, it ispossible to arrange my improved unit to provide a tie or band over sucha support in the region of negative moment for the purpose ofrestraining the concrete in compression. The reaction of the supporttends to squeeze the concrete longitudinally of the beam, so if theconcrete over the support is enclosed within a band of the proper shapewith the ends of the band securely fastened together, or extended forbonding in the concrete, it will be obvious that the compressivestrength of the concrete in this region will be increased in the samemanner that the strength of spirally reinforced columns is increasedover concrete columns provided with plain tied reinforcings.

It should be understood that my improved unit does not depend onencasement in concrete in order to develop its full structural strength.The diagonal tension elements can either be anchored in the body of theconcrete as described above, or by fastening them to a rigid metalliccompression or handling member, as would be the case with a fabricatedjoist. For this reason, the extra concrete on the sides and bottom of abeam, which are ordinarily employed for bonding the bars and for fireprotection, can be omitted on joists used in fire-safe or protectedconstructions, thus rendering possible the use of joists with websone-fifth to one-third of present requirements, or a saving of from 67to 80 per cent in web thickness. This arrangement is possible because ofthe higher unit shearing stresses obtainable as compared with the usualreinforcing in concrete beams or joists having a full. web section atbearing.

These and further objects of my invention will be set forth in thefollowing specification, reference being had to the accompanyingdrawings, and the novel means by which said objects are eifectuated"will be definitely pointed out in the claims.

In the drawings:

Figure 1 is a diagrammatic elevation of a simple beam in partialcompression at the point of maximum moment.

Figs. 2 to 5, inclusive, illustrate the distribution of direct stress atvarious points of the beam shown in Fig. 1, corresponding to the sectionlines Z to 5, inclusive, respectively.

Fig. 6 is a diagrammatic elevation of a beam in which the center sectionis in complete compression.

Figs. 7 and 8 show diagrammatically the distribution of direct stressalong the section lines I and 8, respectively, in Fig. 6.

Fig. 9 illustrates the distribution of shearing intensity in a sectionunder partial compression, that is, a section between the lines 3-3 inFig. 1.

Fig. 10 illustrates the direct stress variation in a section under fullcompression.

Figs. 11 to 13, inclusive, illustrate diagrammatically the compositionof the shearing intensity with full direct compression on any givensection.

Fig. 14 illustrates a typical reinforcing unit for a simple beamsubjected to positive bending, the tension elements being shown insubstantially the correct theoretical position for the best results.

Fig. 15 illustrates a typical reinforcing unit intended to resistnegative moment over a support.

Fig. 16 illustrates diagrammatically an ar- 19 illustrate practicalforms con- 7 stituting variations from the theoretical'shaping of myimproved unit where building codes do not permit the bending of bars asrapidly as my theory of design permits, or where there is a considerabledifference in the cost of base bars and small bars, a r a Fig. 20 is asectional view taken along the line 20 in Fig. 14, showing the preferredlaminated section at the point of maximum moment, this section beingparticularly desirable for the reinforcing units shown in Figs. 14 to17, inclusive.

Fig. 2l is a'sectiontaken along the line 2| in Fig. 18 atthe point ofmaximum moment,this sectional arrangement being preferable for thecompact forms shown in Figs. 18 and 19.

Fig. 22 illustrates the'application of my improved unit to' joistconstruction designed for uniform load. 7

Fig. 23 is a section along the line 2323 in Fig. 22; looking in thedirection of the arrows.

Fig. 24 is an elevation showing the application of my improvedreinforcing unit in conjunction with or supplementing a structural beamwhich is fireproofed with concrete, or other suitable material. 7

Figs. 25 and 26 are sections along the lines 25.25 and 26-46 in Fig. 24,respectively, looking in the direction of the arrows.

Figs. 2'? and 28 are elevations showing the use of plane andthree-dimensional curved anchorage members, respectively, for use withT-beam reinforcements, while Fig. 29 is a plan view of the anchoragearrangement shown in Fig. 27, it being understood that the same planecurvature also obtains for the three-dimensional curved bar shown inFig. 28. I p

Figs. 30 and 31 are plan views illustrating variations of the curvedanchorage members as attached to one or more cross. pieces for. useWhere the T-reinforcement attached to the main reinforcing diagonaltension elements are liable to become entangled during'shipment. a

Fig. 32 shows a welded tie or band for rein- V forcing the region ofnegative moment over the support, as shown in Fig. 15.

Fig.33 shows a modification of a similar type of tie wherein the ends ofthe tie instead .of

being securely fastened to each other, are extended for bonding oranchorage with theconcrete. I 7 a Fig. 34'is ahalf elevation of auniformly loaded, rectangular, simple, concrete beam showing therelation of my improved reinforcing thereto under conditions of low endrestraint.

Fig. 35 is a view. similar to Fig. 34, but in which the reinforcing isarranged to'resist severeend restraint. Fig. 36 is an elevation of apart of a uniformly loaded, continuous, rectangular beam showingseparate reinforcing members for resisting negative bending over anintermediate support and positive bending in that portion of the beambetween a pair of adjacent supports, the relation of the intermeshingshear prongs which carry the load to the top of the support, and bandsencircling the prongs'for preventing spreading of Fig. 37 is a viewsimilar to Fig. 36, but showing the negative and positive reinforcingmembers joined to provide a unitary reinforcement.

Fig. 38 is a half elevation of a concrete beam of simple span showingthe preferred arrangement of the reinforcing member under a condition offixed, concentrated loading.

Figs. 39 and 40 show reinforcing details that may be used in connectionwith any of the modifications of my improved reinforcement and areparticularly desirable in heterogeneous constructions intended tosupport moving loads.

Fig. 41 shows the applicationof the reinforce ing detail illustrated inFig. 39 to a concrete beam of simple span which is otherwise providedwith my improved reinforcing and intended to support a movingconcentrated load.

Fig. 42 is an elevation of a continuous beam subject to reversiblestresses such as occur in a building under wind loading and which isproelements interposed between the flanges for the purpose of resistingdirect tension and preventing flow of the concrete in which theprincipal beam and the reinforcing are embedded, the concrete withinwhich the system is embedded being omitted for sake of clearness,

Fig. 45 is a section along the line 45-45 in Fig. 44, looking in thedirection of the arrows.

Fig. 46 is a half elevation of a simple, concrete, T-beam incorporatingmy improved reinforcing V Fig. 47 is a section along the line 4141 inFig. 46, looking in the direction of the arrows, and showing one type ofreinforcing that may be employed in the T of the beam.

Fig. 48 is a section similar to Fig. 47, but showing a T-beam having alarger cross section and a wider T, and'a modified type of reinforcingin the T of the beam for preventing flow of the concrete under aconcentrated load as well as resisting bending. V

Fig. 49 is a cross section of a'T-beam having a T only on one side ofthe Web and showing a reinforcing in the web for resisting directtension and shear and a reinforce in the 'T-portion for assistingcompression of the concrete in the T.

Fig. 50 is an elevation of a reinforcement that of the prongs fromthesame reinforce; a

Before discussing in detail the various modifications which my improvedreinforcing unit may 7 assume, reference will first be had to Figs. 1to;13,' inclusive, for the purpose of briefly discussing the theory ofdesign upon which the unit is based and also to list the severalformulas which may be employed to determine the direction and amount ofthe stresses operating throughout the beam.

linked relation and a band encircling one or more The theory oflaminated reinforcing design essentially differs from present designtheories in that the shear prongs localize the direct stress at thepoint of maximum moment and restrict this stress as much as possible tothe compression face of the beam. Beginning with a maximum directcompressive stress at the extreme fiber of the beam at the point ofmaximum moment, the triangle of compressive forces increases in depthtoward the bottom of the beam so that the summation of the compressiveforces in the concrete at all times equals the tensile forces in thesteel. This triangle when the cross sectional area of the steel issufficient becomes a trapezoid or parallelogram of forces. The resistingmoment in either case will be the product of the amount of compressiveor tensile force and the lever arm or distance between the centers ofgravity of these forces.

The resisting moment, M, at the point of maximum moment of a.rectangular concrete beam having a laminated reinforcing unit can bedetermined by the following formulas when the section at the point ofmaximum moment is in partial compression, reference being had to Fig. l,which shows a side elevation of a characteristic beam and also to Fig. 2which shows the direct stress distribution at the point of maximummoment.

The factors in the above formulas may be identified as follows:

b=breadth of the beam. d distance from compressive face to center ofsteel, effective depth. fc maximum unit concrete compressive stress atpoint of maximum moment. fs=unit stress in steel, 7cd=depth of triangleof compressive forces. gcl distance from compressive face to center ofcompressive forces. id distance from center of steel to center ofcompressive forces. As Area of steel at point of maximum moment.

When the complete section at the point of maximum moment is incompression, the following formulas apply, reference being had to Figs.6 and 7:

In formulas 204 and 205, the following additional factors are identifiedthus:

f,=unit compressive stress on concrete at bottom of trapezoid ofcompression at point of maximum moment.

A p= =rat10 of steel area to concrete area.

In order to determine the magnitude of the direct compressive stress atany point in the beam other than the point of maximum moment, it isassumed that the ordinates of the locus of the centers of pressure,referred to the longitudinal center line of the beam, are proportionalto the bending moment diagram,these ordinates at the point of maximummoment being indicated in Figs. 1 and 6 and denoted as qd. In arectangular beam where the section at the point of maximum moment isonly partially in compression (See Figs. 1 and 2) there would be alength of the beam (see Figs. 1 and '3) extending on opposite sides ofthe point of maximum moment in which the direct compression zone dropsfurther and further down toward the extreme lower fiber of the beam, asillustrated by the curved l ne in Fig. l and marked thus, Edge of directcompression zone, this zone extending between the section lines '4-4. Atthe ends of the beam, or outwardly of the sections denoted by the lines4-d, there will be portions of the beam in which the sections are infull compression, as shown in Figs. 1 and 5.

In a rectangular beam where the full section at the point of maximummoment is in compression, as shown in Figs. 6 and '7, the condition ofstress at other points is illustrated in Fig. 8.

Since the etxernal bending moment equals the exerted, internal resistingmoment, and the lever arm or the distance from the center of pressure tothe center of the tension steel can be determined by the assumption thatits ordinates referred to the longitudinal center line are proportionalto the bending moment at the section under consideration, the totalamount of direct force exerted at the section may be computed and alsoby straight line interpolation the direct compressive stress at anypoint in the section.

In order to determine the distribution of the gross shear or todetermine the unit shear of any section of any beam, the followingconsideration applies. For the sections in which the direct compressiveforce varies from a maximum at the extreme fibre of the beam to zerolower down in the beam, as in Fig. 3, for the zone of partialcompression, there will be a parabolic distribution of the gross shearas illustrated in Fig. 9, with zero shear at the extreme compressivefibre and maximum shear where the direct compressive force becomes zero.

To determine the unit shear for sections in which the direct compressionis uniform for the entire section, as would occur directly over asupport in a simple beam, the parabolic distribution of shear isillustrated in ,Fig. 12, with no shear at the extreme fibre and maximumshear at the center. For sections in full, direct compression, asillustrated in Fig. 10, the gross shear is proportioned according to themagnitude of the varying direct force (]f), as illustrated in Fig. 11,and the magnitude of the uniform direct force (1), as illustrated inFig. 12, and combined to determine the unit shear for any point in thesection as illustrated in Fig. 13.

The outline given in the preceding paragraph will enable any onefamiliar with the mechanics of material to determine the direct unitcompressive force (1) and the unit shearing stress (0) at any point inthe beam.

By using the established formulas for homogeneous beams as givenimmediately below, it is possible to accurately determine the intensityof the combined unit compressive stresses (0) and the combined unittensile stresses (t), as follows:

longitudinal center 'line of the beam, may be determined by thefollowing formula:

tan 20 The direction of the combined tensile stress 12 is at rightangles to the stress marked 0.

The amount of steel required to reinforce the 7 body ofthe beam againstdiagonal tension need not be calculated, since the diagonal tension orShear is the dropofi in the direct tensile stress Near the top center ofa simple uniformly loaded in the bottom of the beam. The fibers of thesteel, separated-from the main body of the steel as they are no longerrequired for the direct tensile-stress and bent in the direction of thecomputed combined tensile stresses, will resist these combined tensilestresses if properly anchored near the compressive side of the beam.

By applying the formulas listed above, it can be demonstrated that thefollowing condition is true. Theshape of the diagonal tension elementsas they depart from the main body of the reinforcing depends uponwhether the full section at the point where the bar is bent is in directcompression. In a simple beam, for example, application of the formulasconclusively show that the diagonal tension stress is inclined atsubstantially degrees along the bottom of the zone of full compression,along the edge of the zone of direct compression, and in the body of thebeam directly above the support. Accordingly, the diagonal sectionelements should leave the main body of the reinforcing in the fullcompression'zone with a comparatively sharp bend,

, but, in the zone of partial compression, they should 'leave the mainbody with an easy curve to prevent their straightening out under loadand pulling the concrete apart. l

At the compressive face of the beam, or at the 'face having the greatestdirect compression, the

theoretical direction of thejdiagonal tension elements is at rightangles to the longitudinal center line of the beam. The sharpness of thecurve which is formed near the end of the prongs varies according to itsposition in the beam. For example, toward the end of a simplerectangular beam, the prongs curve sharply from their verticaldirection. at the compressive face because the intensity of the shearingstress increases very rapidly in proportion to the direct stress, whiletoward the center of the beam where the unit shearing stress is: notvery large and the direct stress is comparatively large, the curvatureof each diagonal tension element is comparatively flat.

V In a simple T-beam, the curvature of the ends of each prongis'practically the same as in a rectangular beam near the support, butcloser to the center of the beam, a different condition may occur. Thereason for this difference is that the shearing intensity betweenthe'top and bottom of the T increases with greater rapidity than wouldbe the case in a rectangular beam. The result is that the prongs mayhave a theoretical inclination of substantially 45 degrees at the bottomof the T near the center of the beam.

reinforcing having prongs which depart from the main reinforcing with acurvature whose radius equals the depth of the beam and which terminatein hooks. Increased strengths resulting from a sharpening of thecurvature are discussed in the following paragraph.

The purpose of reinforcing concrete is to prevent or stop the flow ofthe concrete under load. When a concrete cylinder, for example, issubjected to a vertical load, it is shortened in its vertical dimensionand extended in its horizontal dimension, so that it may be consideredas flowing in a substantially horizontal direction. This flow of theconcrete occurs at right angles to the directionof the predominantcompressive force.

beam, where the compressive forces are parallel to the longitudinalcenter line of the beam, the flow is in an upward direction, so that itis desirable to place the shear prongs in the same direction. In acontinuous beam, that is, one which rests on intervening supportsbetween the ends of the beam, the direction of flow between the pointsof inflection of a fully continuous span is the same as in a simplebeam. When the point of inflection is passed, the direction of the flowover the support is reversed and the tendency is to squeeze the concreteout at the bottom.

' At such intervening supports, or at any similarly applied concentratedload, the reaction load tends to push up into the mass of concrete sothat the flow of concrete at this point is in a generally horizontaldirection, or at right angles to the reaction. The flow of concretefollows the direction of the combined compressive stresses as long asthe influence of the reaction or concentrated load is predominant.However, as soon as the bending action of the beam becomes predominant,the flow of concrete follows the direction of the combined tensilestresses radiating from the top of the beam over the support. Hence, "atieacross the bottom following the direction of the combined compressivestresses and continuous with downwardly ex-' tending prongs followingthe direction of the combined tensile forces, both of which may bedetermined by formula 298 indicated above, will stop this flow ofconcrete; When the support takes the load of only one level of beams, orwith the concrete section in partial compression, this tie willgenerally be shaped like a triangle with curved sides, or it may beshaped as a trapezoid with curved sides. If, however, the support inaddition is intended to carry the load from upper levels of beams whichare transmitted through the beam webs to the support, or if the beamsection is in full compression, the tie is prgferably shaped more like adiamond with curved sides.

There is an essential difference between my method of reinforcing forcompression bymeans of each other after they have entered the directcompression zone. Experiments have proved satisfactory in which theshape of the indicated elements has followed the combined tensilestress, as determined for sections in partial compression, on leavingthe direct reinforcing and after passing through a suitable transitioncurve have then followed the combined compression stress toward theload. The mathematics indicate, however, that their function istensional. My method prevents the concrete from buckling away from thebeam. The other method may increas the tendency to buckle.

In the case of a fixed load, the enclosing element will givemathematically predictable results, if the ends of the prongs pass underthe load in the compression side of the beam, because the pressure ofthe load on the ends of the prongs is sufiicient to prevent flow. In thecase of a moving load, however, it is desirable to fasten the prongstogether in the compression region into a closed loop to prevent flow.It is necessary, in all cases where predictable results are to beconsistently obtained, to fasten the bottom of the enclosure to thedirect tension reinforcing,

Tests of specimens of my design having curved web members directedtoward and under separated, concentrated loads, but having no directcompression reinforcing parallel to the compression edge of the beam,showed marked increase in load-carrying capacity over similar specimenswithout prongs positioned under the loads. The foregoing shows that thecompression resistance of concrete can be increased without requiringsteel disposed in what has heretofore been considered the criticallocation.

On the other hand, tests on other specimens have indicated that directreinforcing, parallel to and near the edge of the beam subject tocompression, is liable to premature buckling, if not properly restrainedby ties anchored in the web. Present practice results in decreasedstrength unless vertical web steel is provided to give a componentstress which my invention considers critical. One of the objects of myinvention has been to provide reinforcing in the form of enclosing tiesor webs of structural beams which are disposed in the criticaldirection.

The increased compressive strength (f+c) of the concrete in a beam withincurving prongs may be expressed for a single enclosure by thefollowing formula:

3.78 AJ, (209) f+c f,,( Where f+c=new concrete fibre stress due toenclosure Aq =cross-sectional area of steel in one side of an enclosureQ :total distance on either side of load to sides of enclosure asmeasured along longitudinal center line of beam The other nomenclaturehas already been described in an earlier part of the application. Inuse, the new concrete fibre stress (f+c) is sub,- stituted for the valuefc, as shown in formulas already given for bending resistance.

Referring to Figs. 14 to 33, inclusive, which illustrate different typesof structural units in which the disposition and arrangement of thecomponent bars have been calculated according to the formulas listedabove, and considering first the type shown in Fig. 14 which illustratesa laminated reinforcing unit for a simple concrete beam subjected topositive moment, the numerals 50 to 53, inclusive, designate a pluralityof bars which, for a predetermined distance on opposite sides of thepoint of maximum moment, are arranged in superposed relation and arewelded or otherwise securely fastened to each other to prevent relativeslip-ping. The weld may be continuous, or intermittent lengths ofcontinuous weld, or groups of spot welds placed at sufficiently closeintervals may be employed, thus preventing the initial slippagecharacteristic of the mechanical clamps or bands used in the compactsystem of reinforcing. At different distances from the point of maximummoment, these bars are bent upwardly out of the plane of the centersection of the reinforcement to formprongs, as stress conditions demand,the point at which each bar is bent and the nature of the angle or thedegree of curvature which the prong makes with the horizontal portionbeing determined by suitable formulas selected from the foregoinganalysis. As indicated, each bar, up to and at the point where it isbent, is securely anchored to the other similar bar portions so that thelatter are definitely restrained against relative slippage andseparation. In the characteristic unit shown, it will be noted that thecurvature of the prongs progressively increases, respectively, inwardlytoward the point of maximum moment, and that their angle with thehorizontal also progressively increases in the same direction. The endsof each of these bars are generally formed as hooks 54 in order tosecure firm anchorage with the concrete and to prevent relative flow ofthe concrete along the bar. Attention is particularly directed to thedisposition of the curved prongs and the analogy which they bear to asack contain ng grain, as regards the uniform distribution of thestresses along the bars.

It will be understood that while the particular disclosure in Fig. 14shows a laminated center section with the prongs formed by bending upthe bars from this section, the invention is not to be so limited, sincethe center section may or may not have a laminated construction, and theprongs may or may not be continuations of the bars comprising thelaminations. In other words, the prongs may be attached to the centersections, as by welding or other suitable devices. In any case, however,the construction is featured by certain very important characteristics.As clearly shown in Fig. 14, the diagonal tension elements are not onlycharacterized by varying lengths, but by varying horizontal projections.Moreover, the degree of curvature of the diagonal tension elements, asthey depart from the beam face of greater compression, decreases as theyadvance toward the intermediate portion of the main body of thereinforcing having the maximum cross section.

In Fig. 15 is illustrated a laminated reinforcing unit having a shapepreferred for resisting negative moment in a beam which rests on anintervening support. In this arrangement, the bars 55 to 58, inclusive,occupy substantially the same relation as do the :bars 59 to 53,inclusive, shown in Fig. 14, except that in the former case thearrangement of the bars is reversed and also excepting for thedisposition of the ends of the bar 55 which are merely extended in astraight line to resist the simple tensional stresses and also toprovide the necessary bond with the concrete. The bars 59 and 68 areformed as ties having a general trapezoidal shape in which three of thesides may be curved and in which the ends of the bars are securelyfastened to each other to complete the tie enclosure and to prevent flowof concrete due to the reaction, of the support. In this connection, itshould be noted that the bars to 58, inclusive, provide for eitherdirect tension or diagonal tension, but do the structure to act as achairfor the purpose of insuring the correctposition of the'reinforcing,although tests indicate a reasonable proportion of such elements may berelied on to increase the compressive resistance of the beam in which itis embedded.

In Fig. 16 is illustrated a possible form of the unit wherein the barsare shaped so as to provide continuous tension elements near the pointof inflection where a beam changes from positive to negative bending,the ends of the bars which lie near the bottom of the beam to resisttension stresses being bent upwardly to lie close to the upper fiber ofthe'beam over the support to resist tension stresses in this location.This arrangement is intended as a substitute for the characteristicconstruction wherein reliance is placed on the overlapping of thetension elements of the positive and negative moment units.

Fig. 17 shows a simple laminated construction, showing a suggestedmanner in which the bars may be bent on the job to avoid entangling inshipment. V

In Figs. 18 and 19 are illustrated modifications of the preferred formsof structure shown in Figs. 14 and 15, and which it is contemplated maybe employed in regions where building specifications would not permitthe bending of bars according to my improved theory of design; .Inthelaminated type shown in Fig. 18, the ends of the bentup portions ofthe bars, instead of being formed as hooks, as in Fig. 14, may be tiedtogether by simple bars, such as 62. Similarly, in Fig. 19, thedownwardly-extending, bent portions of the bars may be joined by simplebars 63, Fig. 19 being intended as a possible substitute for thepreferred type shown in Fig. 15.

In Figs. 22 and 23 is illustrated the application of my improved type ofreinforcement to fabricated joists, in which the numeral 68 designatesthe bars, arranged generally similar to the bars shown in Fig.14, whichare intended to resist the direct and diagonal tension stresses. Thebent-up ends of these bars are connected to a metallic handling orcompression member or members 69, which may have theangle section shownin Fig. 23, and which may also be utilized as the support for a floorslab construction H3. Where the compression member 69 supports such aconcrete slab, the anchorage H may be pro vided by shearing prongs outof the members 69,

7 or by attaching to 'the'member 69 anchorage devices similar to thoseindicated by the numerals 82, or [65, or I66, in Figs. 29, 47' and 48,respectively. The compression forces in the web are furnished by theconcrete 12, as shown in Fig. 23. The compressive resistance of the web.may be increased by the use of additional enclosures, such as thoseillustrated in Figs. 39 and 40. In cases where the concrete web is notcast on the job, it is desirable to connect the top member 69 to thebottom main tension member as a precaution against damage in handling.Conventional methods of strengthening, such as separators to reduce theunsupported length of the'handling member 69 or plates'to reinforce thecantilever end, may be used on heavier joists. All members of thisconstruction, except the web 12, are fastened together by welding orother appropriate fastening means. The concrete for the web i2 may beplaced with the framework of the joist lying on its side on a form.

In Figs. 24 to 26, inclusive, there is illustrated an arrangement of myimproved reinforcing in conjunction with and assisting structural beamsi3 which are fireproofed with concrete and rested tion shown in Figs. 24to 26, inclusive, will be obtained by positively connecting thereinforcing to the structural beam, as by Welding or otherwise, so thatthe metallic portions of the unit proper will be intimately associated.

Figs. 27 to 29, inclusive, illustrate novel and practical forms ofanchorage for T-beams wherein the anchorage in the T-portion of the beamwhich engages with the ends of the bent bars 88 in the web may be shapedwith a simple plain curve denoted by the numeral 82 in Fig. 27, or itmay possess the three dimensional curve indicated by the numeral'83 inFig. 28, it being understood that, in plan view, each anchorage isshaped with the curve designated by the numeral 82 in Fig. 29. The Treinforcement in these figures is welded to the prong 89. When the Treinforcement is shipped separately, provision should be made for a hookor anchorage at the end of prong 89 to insure the cooperation of the Treinforce with the main reinforce.

In Figs. arrangements for. spacing the cross pieces 84 intended asanchorage members in a T-beam by means of a member or members 85 inorder to prevent entangling of the parts during shipment.

In Fig. 32, the numeral 88 designates a welded tie or band forreinforcing the region of negative moment over a support, such as isillustrated in Fig. 15, the ends of this band being welded or otherwisefastened together. The numeral 81 in Fig. 33 designates a modificationof this tie in which the ends of the tie are not fastened together butare extended to provide the members 30 and 31, there are illustratedtwo' 38 which are bonded in the concrete and therefore resist thetendency of the enclosed portion of the tie to spread under the pressureof the support.

In employing theillustration of a sack of grain to explain the nature ofthe stresses operating in a heterogeneous beam, it should be rememberedthat a sack will restrain the grain in it if the flaps Y The fact is notrecognized vertically and curving in toward the load, rather than on thehorizontal reinforcement in the compressive zone. i

Referring to Fig. 34 which illustrates a portion of a uniformly loaded,rectangular, simple beam, the numeral 90 designates a typical supportupon which rests one end of a beam 9| that is provided with areinforcing, generally indicated by the numeral 92, and which may be ofthe general type illustrated in Fig. 14, except as presently indicated.In this modification, the diagonal tension and shear prongs 93, 94, and95 have their 'ends curved and respectively attached to prongs 94, 95,and 96, thereby forming enclosures having curved ends and within whichthe concrete is held against any tendency to fiow occasioned by thereaction of the support 90. A' reinforcement of this type is moreparticularly intended for beam structures subjected to low endrestraint. Fig. 34 illustrates the conditions at'an'exterior support,but may be used over an interior support if the members 93, 94, 95 or 96are more sharply curved, as indicated, for example, in Fig. 38, and theend of the member 96 is extended sufficiently to be held by the load.

In Fig. 35, there is illustrated a beam arrangement somewhat similar tothat shown in Fig. 34, but under conditions in which the beam issubjected to severe end restraint. The numeral 91 designates a typicalreinforcing according to my invention, but in this case, the diagonaltension elements 98 and IOI form continuations of each other, and areconnected by a curved, metallic portion I02, while the similar elements99 and I are likewise related and are connected by a curved, metallicportion I03 which is fastened to the portion I02, thereby providing asection for resisting end restraint, that is, negative bending, which isoffset from the part of the reinforce that resists positive bending.

In Fig. 36, there is illustrated a system of reinforcing for resistingpositive and negative moments in a uniformly loaded, continuous,rectangular beam that is immediately carried by a support. In thisfigure, the numeral I designates a concrete beam which rests at somepoint intermediate itsends on a support I04. Embedded within the beamover thesupport is one of my characteristic reinforcing members I06 asillustrated in Fig. 15 and having the usual intermediate and laminatedportion formed by appropriately connecting a plurality of bars, thislaminated portion being embedded within the beam adjacent the upper sidethereof and incorporating an enclosed tie I0'lformed by suitablybendingone of the component elements of the reinforcing member, the tie I01being located immediately over the support I04 and intended to restrainthe fiow of concrete in this locality. The tie I 01 may possess thesimple circular shape indicated, but in many cases would approximate thetheoretically correct shape illustrated in Fig. 32. The reinforcingmember may also include at'each end a downwardly curved prong or elementI08 for resisting diagonal tension and shear, straight prongs orelements I09 and I I0 for picking up the load from the mid-span of thebeam, and also a reinforcing element II I which acts as a reinforceagainst conditions of partial loading, These prongs or elements extendfrom the intermediate portion inthe manner above described.

In the mid-span to the right of the support I 04,'there is locatedwithin the beam, a positive reinforcing membe'rI I 2 as illustrated inFig. 14

and disposed with its intermediate portion adjacent the lower side ofthe beam to. resist horizontal tension in this locality. The member II2also includes an element II3 which extends toward the support I04 andreinforces the beam against conditions of partial loading, and elementsH4, H5, and H6 which are located in substantially intermeshing oralternating relation with the adjacent elements I09 and H0, all asclearly indicated in the figure, these cooperating elements acting tocarry the load up to the top of the support. Curved element Ill may beprovided for resisting diagonal tension and shear. It will be understoodthat the opposite end of the reinforcing member I I2 may be identicalwith that actually illustrated in the figure and the latter end may belocated in the same relation to a negative reinforcing member providedover another support, or may be located in the beam generally asindicated in Fig. 14, dependent upon the structural conditions. In thismodification, it will be understood that the negative and positivereinforcing members constitute separate structural elements. Moreover,each of the elements which extends away from the intermediate portion ofthe associated reinforcing member is preferably provided at its end witha hook in order to secure firm anchorage with the concrete and toprevent relative flow of the concrete along the element, all asdiscussed generally in connection with the type of reinforcingillustrated in Fig. 14.

Preferably, the shear prongs I09 and H4 are encircled by a metallic bandI09 and the prongs I H0 and H5 by a similar band 5 These bands may belocated at any point intermediate the ends of the associated prongs andthe bands may be spaced from each other. Their purpose is to preventspreading of the concrete under the opposing pull of the prongs whichpass therethrough.

In Fig. 37 is illustrated a structural condition substantially identicalwith that illustrated in Fig. 36, the only distinction between thesemodifications residing in the fact that, instead of providing twoseparate reinforcing members to provide for positive and negativebending in the beam, a single reinforcing member H8 is employed. Thearrangement of the component elements of this member is identical withthe form shown in Fig. 36, except that the positive and negativeportions of the reinforcing are positively and unitarily connected afterthe general manner illustrated in Fig. 16. The strength of the positivereinforce II8 will obviously vary with the conditions of loading andspan. Accordingly, it may be as shown, or it may be considerably reducedin cross section and might consist of a single bar forming acontinuation of one of the diagonal prongs from the negative reinforce.

In Fig. 38 is illustrated a concrete beam of simple span which issubjected to a fixed, concentrated load. Under these conditions thereinforcing member II9 may be arranged generally as indicated in Fig.14, that is, with the usual intermediate portion I20 for resistinghorizontal tension and hook-ended prongs or elements I2I extendingtherefrom for resisting diagonal tension and shear. In order to resistthe effect produced by the concentrated load, however, an enclosed tieI22 is associated with the intermediate portion I20 and positioneddirectly under the concentrated load in order to prevent flow of theconcrete in this locality. This condition of loading, therefore,approximates that found ma beam that intermediately carries a load orsupport which provides a condition of concentrated loading. The tie I22may be formed by suitablybending a separate bar of metal intosubstantially the circular shape shown, or intothe shape illustrated inFig. 32, and thereafter suitably attaching, as by welding, the same tothe intermediate portion I20, or this tie may be formed-by suitablybending the uppermost bar of the intermediate portion to form a loop andthereafter continuing the bar to provide the associated diagonal tensionor shear prong, as indicated inFig. 40;

It has beenstated that increased compressive resistance in the concretemay be obtained by the useofenclosures properly shaped and attachedtothe'direct reinforcing. When these enclosures are overlapped, they maybe made to accommodate moving loads and to obtain greater increase incompressive strength than would be possible with the same amount ofmetal in a single enclosure; The 'purpose of enclosures is' torestrainthe tendency ofthe concrete under com press ion to buckle or breakawayfr om the main body of thermal. The vertical tensile stress in thebody of the beam induced by this tendency to buckleinreass toward thelongitudinal center line of the beam as the amount of concrete tendingto breal; away becomes larger.

c When enclosures overlap, it is particularly desirable to fasten themattheir points of contact, t e crea n n ide n osu e o al e ume and a webreinforcing characterized by apexes of varying height in the compressionside,

the apexes being the intersecting or contacting points of theenclosures, Points of this nature are more clearly shownin Fig. 42. Theinside enc osu es. ive la e nc e e in u pressive stress because theyenclose a smaller volume of concrete. The advantage of fastening the,overlappinguenclcsu s at their touching points is that the concreteatthe center, which is subjected .to greater vertical tension from thebuckling tendency, is surrounded by more en closures than concrete nearthe compression face.

Referringto Figs.;39 and 40, there are illustrated types ofreinforcings, for beams subjected to moving loads it being understoodthat these 7 forms may be'otherwise associatedwith my char:

acteristicforms of reinforcing including an intermediate portion for.resisting horizontal tension and diagonal tension. or shear prongs orelements associated therewith; .In .Fig. 39, the reinforcing detail isformed by a. plurality of enclosed. ties I23. which are, arranged in theoverlapping relation indicated and. which. are preferablyfastenedtogether at their points. of intersection I24 to form smallerenclosures than those encompassed by. each. tie with a correspondingreduction in height of the apex of each small enclosure, andalso at thesurfaces where they touch, denoted generally by the numeral I25, thusproviding a plurality of enclosures for resistingspreading ofthe'contained material. In Fig. 40 the reinforcing detail is formed by,successively bending a bar of metal I26 into; a succession of spacedenclosures I21, each enclosure being fastenedat the point designated bythe numeral I28 in order to retain its prefixed shape.

'While the enclosures illustrated in Figs; 39 and 40 are denoted asbeing circular in form, structural conditions'may dictate theshapeillustrated in. Fig. 32. Each. of these reinforcing details isuseful for resisting moving loads, or maybe employed in walls wheresettlements cause high shearing stresses with little bending.

In Fig. 41 is illustrated the application of the reinforcing detailshownin Fig; 39-to a concrete beam of simple span which is subjectedto amoving load, the numeral I29 designatinga series of enclosing elementswhich are related generally as indicated in Fig. 39 and which aresuitably spaced according to the probable position of the moving load.This detail I29 .is fixedly attached to my characteristic reinforcingmember I30 which may beprovided with the usualelements I3I for resistingdiagonal tension and shear, the entire reinforcing being embedded in aconcrete beam indicated by the numeral I32. Over the support I33, thereinforcing member preferably incorporates elements I34 which areconnected to each other and to theadjacent diagonaltension element. I3Iby curved portions I35 for resisting end flow, as, generally discussedinconnection with Fig. 34.. I

In Figs. 42 and 43 is illustrateda beam I36v which is subject toreversiblelstresses, suchas occur in a building under wind loading. Em.-

bedded inthe concrete composing this beam-is a reinforcing e1ement,l3'lwhich maybe com.- posed of one or more bars suitably connected togetherto prevent relative slippage and which is locatedadjacent the lower.side of the beam and a similar element I38I ,positioned adjacent theupper sideof the beam, theseelementsproviding for positive and negativebending, respectively. These elements are further positively fastened toa plurality of enclosin elements I39 5 of the general type indicated inFig. 39 and the spacing of these elements willldepehd upomthe probableposition and direction of the load to which the beam is subjected; Fig.43 illustrates the relation of the elements I3 'I--and. I38 to-xtheenclosing elements I39.

Fig. 44 illustrates a filrthermodificatlonof my improved reinforcing asapplied to a structural beam I40 which, in thepresent instance,isindicated as being an I-beam having-the usual in;- termediate web'I4Iand thetransversely. extend: ing flanges I42 at the top and bottom ;of-;the web. It is contemplated I that this.-structural beam will beembedded in concretea-nd in order to properly reinforce theconcreteagainst flow andfor resisting direct tension stresses, one. side of thebeam.may have embedded inthe, concrete between the flanges. I42areinforcing member I43 comprising an elongated loop formed/by suitablybending a bar, this loop. having-,jhe curved ends I44 and the flattop,.-andbottom sides I45, which are fastened to'theflanges I42; --Asimilarly shaped reinforcing-member- I4B, 1but shorter in length, ispositioned withinthe member I43. with its .flat 1top-and bottom sidesI4] fastened to the sides I45 tor -prevent .relativelslina page and itscurved ends I48 spacedfrom the ends I44. A parti-circular bar I 4'9 issecuredto each end I48 and to the member I43 in comple:

mentary relation to the adjacent end I44 so provide at eachend ofthebea-m asubstantially circular enclosure I50. A bar I5 I, shapedlikethe bar I49 is'secured at each end of and withinlthe member I46 incomplementary relation ;to -th e adjacent curved end I48 toprovidesubstantially circular enclosures I52. Betweeh thiekbars I,5;I islocated a plurality of circularly bent' -bars ljia, providing asuccession: of equirspacedi enclosures I54! The 'S Q 91Y he s a eh tweethe des, '4'! an r fastened: heret eswell-ss to each other at theirpoints of contact. There is thus provided along the beam a succession ofenclosures which are embedded in the concrete and effectively restrainthe same against flow.

On the opposite side of the web, a similar reinforcing system, denotedgenerally by the numeral I and indicated by dotted lines, is employed,but preferably shifted endwise with respect to the system shown in fulllines a distance equal to one-half of the diameter of a full lineenclosure. Considering the entire beam as a unit, then, the enclosureson opposite sides of the structural beam are positioned in overlappingrelation. A

The systems on opposite sides of the web may be spaced therefrom, asillustrated in Fig. 45, or may be placed with their side surfaceswelded, or otherwise fastened in touching relation, to the beam web. Itwill be understood that the enclosures of each systemin Fig. 44 may havethe circular form shown or they may have the form illustrated in Fig.32.

In Figs. 46 to 49, inclusive, there is illustrated the application of myimproved reinforcing to a simple concrete T-beam. In Figs. 46 and 47,the numeral I56 designates my typical reinforcing which is located inthe web portion of the beam I51 and which is provided with the usualelements I58 for resisting diagonal tension and shear. Associated withthe reinforcing member I 56 may be a pair of elements or prongs I59which are connected to each other by a curved portion I60 for resistingend flow overa support I6I as already discussed in Fig. 34; The diagonaltension elements I58 extend upwardly into the T-portion of the beam forconnection to the T reinforcing members indicated generally by thenumerals I62, I63 and I64 whose shape and arrangement may correspond,respectively, to the reinforcing details illustrated in Fig. 27 or 28.The arrangement of the rinforcing members I62, I63 and I64 may vary,that is, they may be placed flat in the T of the beam, but arepreferably upright or curving toward the point of maximum moment, Fig.46 illustrating a characteristic condition. Preferably, theT-reinforcing illustrated in Fig. 46 should theoretically curve from the45 inclination of the shear prong in the web of the beam to which it isattached, through at least a sufficient angle to occupy a position atright angles to the extreme compressive fibers of the concrete in thesame manner as the prongs ina rectangular beam. Fig. 47 illustrates moreclearly the detailed arrangement of the reinforcing in the T-portion ofthe beam where the reinforcing is arranged in an upright position. Asindicated, this T-reinforcing corresponds generally to my characteristicreinforcing, as illustrated in Fig. 14, in that it is composed of aplurality of bars securely fastened together and from which prongs orelements I65 depart, each of the prongs being preferably provided withhooked ends for reasons already noted.

Figs. 48 and 49 illustrate types of T-reinforcing which additionallyincorporate enclosing members I66 and I61 for the purpose of resistingspreading of the surrounding material, Fig. 48 showing a T-beam having alarger section and a wider T than the beam illustrated in Fig. 47 andFig. 49 showing a T-beam having a T only on one side of the web. Theelements comprising the T-reinforcing may be formed of either flat orround bars, but will ordinarily be composed of light wire because of therelatively small stresses encountered in this portion of a T-beam.

In Fig. 50, there is illustrated a-variation of the structuralreinforcement illustrated in Fig. 15, but intended for use in wallcorners or to provide end restraint in an exterior column. Thisreinforcing detail is indicated by the numeral I68.

and it incorporates an enclosing tie I69 for resisting spreading of theconcrete and may have permanently fastened thereto the elements I10 andHI which are shaped to conform to the corner shape of the structuralmember and provided with hooked ends.

In Fig. 51, there is illustrated a system of reinforcing for resistingpositive and negative moments under conditions similar to thatillustrated in Fig. 36. The numeral I12 designates a concrete beam whichis carriedintermediate its ends on a support I13. A characteristicunitary reinforcing member I14 is embedded in the beam over the supportand embodies an enclosed tie I15 directly over the support, downwardlycurved, shear prongs I16, and straight prongs I11 for picking up theload from the midspans of the beam on opposite sides of the support andalso a reinforcing element I18 for resisting a condition of partialloading. The ends of each prong I11 are preferably hooked and the hookedend of one prong is fastened to the adjac'ent prong I11 to form anenclosure I19. The enclosure I19 might be formed by simply forming areturn bend in the prong I11.

In the mid-span to the right of the support, a positive unitaryreinforce I is located adjacent the lower side of the beam and itincorporates at the end adjacent the support a pair of prongs I8I whichextend upwardly toward the top of the beam and on opposite sides ofenclosure I19. Within the enclosure, the ends of the prongs I8I may beencircled by a band I82 for resisting spreading of the prongs I8I.

In the beam to the left of the support is alsolocated a positive,unitary reinforce I83 which also includes a prong I84 that extendsupwardly toward the top of the beam. The prong I84 is looped through theenclosure I19 and bent back upon itself in a substantially linkedrelation to the enclosure. The return and upwardly extending portions ofthe prong I 84 may be encircled by a band I85 which acts the same asdoes. the band I82.

It will be understood that, under conditions of relatively low stress,the bands I82 and I85 may be omitted. The linking of the positive andnegative reinforcings may be substantially as il-- lustrated, or thelink construction shown at either: end of the negative reinforce may beused at both:

ends.

It will be obvious that the illustration of specific forms of myimproved reinforcing unit in.

particular structural environments does not preclude the use of any ofthe other forms under the same or similar conditions of operation. Thechoice of a reinforcing unit Will in general depend upon the usualfactors which dictate the selection of a structural design, such aslocation of the unit, and the nature, extent and location of the imposedload.

I claim:

1. A reinforcing member for a heterogeneous beam comprising a pluralityof individual bars securely Welded together to prevent relative slippageand separation and to form a substantially solid, intermediate andlaminated portion having a varying cross section and separated elementsextending from'the portion and making uniform angles therewith forresisting diagonal tension and shear, each bar Within the portion beingsecurely held to the other bars within the portion up to and includingthe point at which the associated element departs. V

2. A reinforcing memberfor a heterogeneous beamcomprising apluralityofbars heldtogether to prevent relative slippage and separation and.

to form a substantially unitary, intermediate and laminated portion, andelements extending from the portion for resisting diagonal tension andshear, one or more of said elements being formed into a closed loop ortie for preventing spreading of the concrete under heavy or concentratedloading, such as overa support.

3..A reinforcing member for a heterogeneous beam subjected toconcentrated loading such as occurs over a support comprising aplurality of bars held together to prevent relative slippage andseparation andto form a substantially unitary, intermediate andlaminated portion having a varying cross section, the ends of one ormoreof the bars being bent away from the portion and secured together,respectively, to form enclosed ties for resisting spreadingof theembedding material under the concentrated load and the remaining barsbeing bent from the portion to form prongs.

4. A reinforcing member for a heterogeneous beam subjected to negativebending moment over a support comprising a plurality of bars held ,thefireproofing comprising a together to prevent relative slippage andseparation and to form a substantially unitary, intermediate andlaminated portion having a varying cross section, the ends of one ormore of the bars being bent away from the portion and secured together,respectively, 'to form enclosed ties for resisting spreading of theembedding material under the reaction ofthe support, and the remainingbars being bent away vfromthe portion to form prongs whose projectedlength in the zone of negative bending decreases progressively.

5. A reinforcing member for a heterogeneous beam comprising a pluralityof bars held together to prevent relative slippageand separation and toform a substantially unitary, intermediate and laminated portion havinga varying cross section, the individual bars being extended away fromthe portion to form prongs, certain of the prongs beyond thelongitudinal center line of the beam making increasing angles therewithtoward the center of the beam, and the ends 'of certain of the prongsbeing secured together to form substantially unitary, end portionsoffset from the intermediate portion, the intermediate and end portionsresisting horizontal tension created by positive and negative moments,respectively.

6. In heterogeneous construction, the combination of a support,fireproofed beams resting thereon, and a reinforcing member embedded inplurality of bars held'together to prevent relative slippage andseparation and to form a substantially unitary, intermediate andlaminated portion located over the support for 'resistinghorizontaltension, elements extending from the portion for resisting diagonaltension and shear, and a second reinforcing member embedded in thefireproofing intermediate the ends of each beam comprising a pluralityof bars securely fastened together to form a substantially unitary,intermediate portion for resisting horizontal tension and elementsextending from the last named portion for resisting diagonal tension andshear.

'7. In heterogeneous beam construction, the combination of a T-beamhaving a plurality of barslocated in the Web of the beamand weldedtogether to prevent relative slippage and separation and to form mediateand laminated portion, said portion constituting the main tensionreinforcing of the beam, and elements extending from the portion asubstantially unitary, interv and cooperating therewith for resistingdiagonal V tension and shear, each bar within the portion being securelyheld to the-other bars within the portion up to and including'the pointat which the associated element departs therefrom.

8. A reinforcing member for a heterogeneous beam comprising a pluralityof bars weldedtogether to prevent relative slippage and separation andto form a substantially unitary, intermediate and laminated portion, andelementsextending from the portion for resisting diagonal tension andshear, one or more of the elements being bent to provide an enclosingformation having bulging sides and adapted to be embedded in thesurrounding material for resisting spreading of the material created bythe concentrated load or support..

9. Areinforcing member for a heterogeneous beam comprising a unitary,intermediate portion, and elements extending from the portion for resisting diagonal tension and. shear, some of said elements being formedintoa curved shape with the-ends of some of the curvedelements directedtoward each other for preventing spreading of the concrete under heavyor concentrated loading, such as over a support.

10. A reinforcing member for a heterogeneous beam subjected toconcentrated loading such as occurs over a support comprising a unitary,inter-, mediate portion for resisting horizontal tension, some elementsextending away from the portion in-arcuated forms with the ends of someof said arcuated elements directed toward each other, respectively, forresisting spreading of the embedding material under concentrated load,and other elements extending away from the portion to formprongs.

11. A reinforcing member for a heterogeneous beam subjected to negativebending moment over a support comprising a unitary, intermediate portionfor resisting horizontal tension, elements extending away from theportion'and diagonally toward each other for resisting spreading of theembedding material under the reaction of the support, and other elementsextending away from the portion to form prongs whose horizontal pro.-jections vary in the zone of negative bending.

12. A reinforcing member for a heterogeneous beam comprising a pluralityof bars held together to prevent relative slippage and. separation andto form a substantially unitary,'intermediate portion, the individualbars beingextended to form prongs, the ends of certain of the prongsbeing secured together to form a substantially unitary, end portionoffset from the intermediate portion, certain of the prongs forming apart of the end portionbeing arranged with a curved shape with'the endsof each curved prong directed toward each other for preventingspreadingof the concrete, the intermediate and end por-' tions resistinghorizontal tension created by positive and negative bending moments,respectively.

l3. In heterogeneous construction, the combination of ametallic-structural beam having a web adapted to be covered by thematerial reinforced resisting diagonal tension and shear, some of saidelements having an arcuated shape with the ends thereof directed towardeach other, respectively, for resisting spreading of the embeddingmaterial.

14. In heterogeneous construction, the combination of a metallicstructural beam having a web adapted to be covered by the materialreinforced and spaced flanges extending transversely from the web, and areinforcing member for embedding in the material adjacent the web andbetween the flanges comprising a unitary, intermediate portion forresisting horizontal tension, elements extending away from the portionfor resisting diagonal tension and shear, some of said elements beingformed into an arcuated shape with the ends thereof directed toward eachother, respectively, for resisting spreading of the embedding materialunder concentrated load.

15. In heterogeneous construction, the combi nation of a metallicstructural beam having a web adapted to be covered by the materialreinforced and spaced flanges extending transversely from the web, and areinforcing member for embedding in the material adjacent the web andbetween the flanges comprising a unitary, intermediate portion forresisting horizontal tension, elements extending away from the portionfor resisting diagonal tension and shear, the end of some of theelements being directed diagonally toward each other, respectively, inthe upper compressive region of the beam to form enclosing -ormationsfor resisting spreading of the concrete under load.

16. In beam construction, the combination of a metallic, compressionmember having ends extended for bearing, and a tension system dependingtherefrom and adapted to be embedded in concrete comprising a pluralityof bars held together to prevent relative slippage and separation and toform a horizontal tension member in the web formed by the concrete andthe embedded tension system, and curved web tension members connectingthe compression and horizontal tension members in the concrete adaptedto exert a compressive force on the concrete, compression in the web ofthe beam being provided by the concrete.

7. In heterogeneous construction, the combination of a T-beam havingunitarily connected, direct tension elements and diagonal tensionelements located in the web of the beam, and other tension elementslocated in the bottom of the T of the beam, a portion of each of saidlastnamed elements adjacent the web of the beam being disposedsubstantially at right angles thereto, and another portion of some ofsaid last-named elements further out in the T from the web of the beamextending in a different direction than said first-named portion, saidlastnamed elements cooperating with the elements in the web of the beam.

18. In heterogeneous construction, the combination of a T-beam havingunitarily connected, direct tension elements and diagonal tensionelements located in the web of the beam, and other tension elementslocated in the bottom of the T of the beam, a portion of each of saidlastnamed elements adjacent the web of the beam being disposedsubstantially at right angles thereto, another portion of some of saidlastnamed elements further out in the T from the web being diagonallydisposed relative to the web of the beam, and one or more of saidlast-named elements being formed into an enclosing loop or tie forpreventing spreading of the concrete, "all of said last-named elementscooperating with the elements in the web of the beam. Y 19.- Inheterogeneous construction, the combination of a T-beam having unitarilyconnected, direct tension elements and diagonal tension elementslocatedin the web of the beam, and a reinforcing member located in thebottom of the T of the beam comprising a plurality of bars held togetherto prevent relative slippage and. separation and to form a substantiallyunitary, intermediate and laminated portion having a varying crosssection, said intermediate portion being disposed substantially at rightangles to the web of the beam, certain of the bars further out in the Tbeing bent away from the intermediate portion and diagonally disposedrelative to the web of the beam, and certain of the other bars formingenclosing ties for resisting spreading of the embedding material underload, the T-reinforcing member cooperating with the elements in the webof the beam.

20. In heterogeneous construction, the combination of a T-beam havingunitarily connected, direct tension elements and diagonal tensionelements located in the web of the beam, and a reinforcing memberlocated in the bottom of the T of the beam comprising a plurality ofbars welded together to prevent relative slippage and separation and toform a substantially unitary, intermediate and laminated portion, theinter- 'mediate portion being located adjacent the web of the beam anddisposed substantially at right angles thereto, certain of the barsbeing bent away from the portion for resisting diagonal tension andshear and one or more of the bars being bent to provide anenclosing'formation having bulging sides for resisting spreading of theembedding material under load, the T-reinforcing member cooperating withthe elements in the web of the beam.

.21., In heterogeneous construction, the combination of a plurality ofmetallic elements adapted to beembedded in the material reinforced, oneof the elements comprising a metallic beam having a web ,and spacedflanges extending transversely from the web, and the other elementscomprising reinforcing members connected to the intermediate portion ofthe beam to form therewith' a unitary, intermediate section for resist"inghorizontal tension, each member having arcuate prongs extendingtherefrom between the flanges, certain of the prongs being directedtoward each other opposite the intermediate portion of the associatedmember for resisting spreading of the embedding material under a load.

. 22. A reinforcing member for a heterogeneous structure comprising aunitary reinforce having r a directtension element adapted forpositioning:

inthe tension side of thestructureand diagonal tension elementsextending from the direct ten- .sion element and adapted to be locatedsubstan-- jtially' inthe longitudinal vertical plane of and directedtoward the compression side of the structure, some of the diagonaltension elements being connected by acurved element in the region oftheexternal force to form an enclosure for resisting spreading of theconcrete.

23. A reinforcing member for a heterogeneous.

structure comprising a unitary reinforce having "a direct' tensionelement adapted for positioning in the tension side of the structure anddiagonal tension elements extending from the direct tension element andadapted to be located substantially-in the longitudinal; vertical planeof and directed toward the compres'sionside-of the structure, someoi-the diagonal tension elements be- .ingconnected by a-curvedelementinthe-region of the external force to: form an enclosure for resistingspreading or the concrete and certain of -the other-diagonal tensionelements being ad- ;jacently directed toward each other.

24. A reinforcing member for a heterogeneous structure comprising aunitary reinforce'having a directtension element adapted for positioning,in-the tension side of the structure and diagonal tension elementsadapted to be located substantially in the longitudinal vertical planeof and directed toward the-compression side of the structure, thediagonal tension elements being connected in the region of asupport'at'the end of the member byes-curved element to form anenclosure for resisting sp'reading of the concrete. A reinforcingmember'for a heterogeneous beam comprising a plurality of bars heldtogether to prevent relative slippage and separation and --to form;a'substantially unitary, intermediate and laminated portion; having avarying cross-sec- 2 5 111011, the-individualfbars being" extended awayfrom'the portion to form prongs,-certa in ,of the :prongsbeyond-thelongitudinal centerline of the beamjmakingincreasing angles" therewith"toward the a center of: the beam, the ends of. cer- :tain'of the prongsbeing secured 'together to 'form' substantially unitary, end portionsoffset from the-intermediate portion, the intermediate and;end'portions' resisting horizontal; tension :created'by positive andnegative moments, re-

5 spectively, and certain-of the prongs. associated {with a portionbeing-directed toward each other :to form enclosing -:ties;forresistingspreading of the embedding material under a concentrated 110m. f

7 "26."In* heterogeneous'construction comprising a concrete beam restingon a supportand ex'- tendingatherebeyond, the combination of a -re- 7infor'cing member;- adapted to -be located in the upper: part ofthe beamover the support comprisingia' unitary, intermediate portion 'forresisting'horizontalten'sion, and shear prongsrdiverging from theportion, ;certain of the. prongs over' the support-being bent intoloneor' more enclosing formations for resisting spreading of the concrete,and a second reinforcing member located in thelowerpart of the beambeyond :the support comprising a unitary, intermediate portion forresisting horizontal tenses; and shear prongs diverging therefrom, theadjacent prongs V "of'the portions being locatedin alternatingrelartion=in;theconcrete, 1 27. A reinforcing member for a heterogeneousbeam-comprising- 'a unitary reinforce-having a "directtensionelement anddiagonal tension ele- 'm'ents'extending therefrom and adapted to bepositioned substantially in th'e -longit udinal ,ver tical plane ofthe,beam;=and directed toward the ;-compression side of the'beam, someofv the diag- "onal tension elements-beingconnected in-the 5Eregion ofthe external forcebycurved elements :forming one; or more" enclosuresfor resisting spreading of theconcreter V 1 r I i"--28::A'reinforcingmember'for a heterogeneous 'structure=cornprising an element forresisting di- T18Ctft8llSiOI1. andan enclosure element for resistingspreading ofthe embedding material, the *fdirect'tension and enclosureelements being immovablyi connected and the enclosure elementbein'gxcurved generallyopposite the connection 7 -offthe:element"s.:' g

29. A r einforcingwmember-f or a heterogeneous structure comprising;anelement for resisting direct tension and 'a-plurality of enclosureelements arrangedinoverlapping relation for resisting spreading of theembedding material, the 5 direct tension and enclosure elementsbeing'connected to form aunitary reinforce, and; the enclosureelem entsbeing fastened to each other to prevent relative slippage and beingcurved generally opposite their connection with thetension element.

30.-In' heterogeneous construction; the con'ibination of; aconcretebeamadapted to rest on a support andto extend therebeyond; a reinforcingmember located in 'the upper part of the 15 beam over the supportcomprising "aunitarygintermediate portion for resisting horizontaltension and diagonal tensionprongs diverging" from the portion,asecondreinforcing" memberlocated in the lower'part of thebeambeyondjthezo support comprising -'a "portion for resisting horizontaltension; and diagonal tension: prongsj-diverging therefrom, theadjacfentprongs ofgthe portions extending toward" eachotheri in1theconcrete, and bands encirclinggroupsf 50f the -25 oppositely extendingprongs to preventspre'ading of -the concrete:

3 1. In continuous heterogeneous beam-construction, the combination of'a-unitary -reinforcing unithaving-ani enclosing member and 30 Vdiagonal tension prongs located over a support,

a second reinforcing unit-having diagonal tension prongs located:between adjacent supports, the adjacent prongs of theuriitsfextendingtowardeach otherrand certain of the-unit'prongs, 35

respectively; being substantially linked to each other, and'a bandencircling'someof :the; diagonal-tension prongsfrom'either reinforce)"32;: In" continuous heterogeneousrbeam ;con-

struction, thecombinati'onpfa unitarysreinforc- ,40 I -ing-unit locatedoverasupportan'd having diagonal tension-prongs; one or more-of theprongs atone end ofstheunitforming an enclosing tie, and asecondreinforcingunit 'locatedin-the lower part or the beam? on one side ofthe support and :45

having diagonal tensiomprongs, the adjacent prongs'of theunitsiextending toward-eachother,

and one or more prongs from'the second-"unit 'being substantiallylinkedtothe enclosinglti'e.

3:; 33. In heterogeneous: construction, i the" coin' 5o binationof ametallic structuralbeamyhaving a j w'eb adapted to" be covered? bythe"embedding i material and spaced flanges :extending transverselyi'fromthe. web,ran'd a plurality ofispaced,

. curvedm'embers fastened to the'beam and a -;55 ranged in successionalong-and in both directions f'frorn the central portion of the beam,the mem bers on opposite sides of the'central portionbeiri'g oppositelycurvedfand being directed toward-the "central portion at their pointsof: connection with: 60 1 the flanges; a

34. A reinforcing member for heterogeneous 'c'onstruction: comprising adirect tension'element for resisting negativebending,such'as "over a 1support, and having immovably 'conriecte'dtheie- 6 to diagonal tensionelements extending there-c fro rn some. of which areieurved to provide,ene' closures located substantially in the plane of application of thereaction force for preventing "spreading of the embedding material, andothers 70 -are extended to form a' reinforce'for resisting posltivebending .in the adjacent span. i v .i

35. "A reinforcing member for a heterogeneous structure comprising asubstantially flatj latticelike member defining a" plurality ofenclosuresflo

